In industrialized countries, lung cancer is among the most common cancers in both genders. In the US (2007), this cancer was diagnosed in 213,380 men and women, and 160,390 men and women are expected die of it. The highest rates are still observed in North America and Europe, but lung cancer is already the most common fatal cancer worldwide, with 1.04 million new cases and 921,000 deaths yearly. Lung cancer accounts for more deaths than breast and colon cancer combined. Unlike breast and colon cancers, there is currently no recommendation in favor of lung cancer screening. The rationale of lung cancer screening is debated mostly because basic principles are misinterpreted. Thus, we first discuss the rationale for lung cancer screening by reviewing the fundamental conditions needed in order to propose a screening intervention. We will review fundamental concepts that are essential to appropriately design and interpret lung cancer screening studies, and will illustrate common systematic errors including lead time bias, length bias, and over-diagnosis. We then review the available tools for lung cancer screening; we will show that, although each tool may detect lung cancer at an earlier stage compared with no intervention, all except low dose CT (LDCT) failed to reduce mortality. Screening studies from 1960 to now will be presented critically, including studies using LDCT, both and observational and experimental, in the US and Europe. Lastly, we will discuss lung cancer screening from ethical and social perspectives. Since smoking is the major risk factor for lung cancer, some argue that the major intervention to decrease lung cancer is to prevent people from smoking or to make them quit, and have further argued that even if lung cancer screening trials report clear mortality reduction, resources should be allocated to smoking prevention rather than screening. We will argue that preventing tobacco use is the key element of lung cancer prevention, and must be therefore encouraged to reduce the incidence (primary prevention). However, this does not preclude the efforts to improve the treatment of lung cancer, and screening (secondary prevention) might be part of these efforts if effective.